"This is a reminder for people to be on guard and be up to date on their vaccinations," said Dr. Umair A. Shah, executive director for Harris County Public Health. "Measles, a serious disease, is in our community."

He added that it's too early to tell if the five new cases could be the beginning of a local outbreak.

Dr. Peter Hotez, an infectious disease specialist at Baylor College of Medicine and Texas Children's Hospital, said measles peaks in the late winter or early spring.